News Release

Release Date: November 20, 2014

How an NETL-Managed Microgrid Demonstration Project Reduced Peak Power Loads and Improved Power Reliability at One of the Nation’s Largest Jails




A California jail, the fifth largest in the nation, hosted a demonstration project managed by the National Energy Technology Laboratory (NETL) that showed how a microgrid can reduce energy consumption and shave thousands of dollars off an annual electricity bill.

A microgrid is a small-scale power grid that can operate independently of or in conjunction with an area’s main electrical grid. In an $12 million project managed by NETL, Chevron Energy Solutions installed a microgrid at the Santa Rita Jail in Dublin, Calif., as part of the Energy Department’s Office of Electricity Delivery and Energy Reliability’s Renewable and Distributed Systems Integration Program.

Several factors are involved in a productive microgrid: dedicated power-generation sources, customer loads, a defined electrical boundary, and a switchable connection to the main power system. The microgrid at the Santa Rita Jail includes a fuel cell capable of producing heat and power, a solar photovoltaic system, wind turbine generators, battery energy storage, backup diesel generators, and smart grid control features.

During the demonstration, the microgrid reduced the jail’s peak power load by 95 percent and reduced energy consumption during peak hours by 98 percent while achieving an annual savings of $110,000 on electricity bills. Operation of the microgrid also reduced the load on the local distribution feeder serving the jail by about 15 percent, reducing wear-and-tear on substation equipment.

Chevron Energy Solutions installed a fuel cell unit at the Santa Rita Jail in Dublin, Calif., as part of an NETL-managed microgrid demonstration project. With completion of the 5-year project, the jail continues to reap the benefits of having its own microgrid.

The microgrid also demonstrated a capability to disconnect itself from the main power grid—called "islanding"—and then automatically resynchronize and reconnect. The islanding capability is important because, if the main grid experiences instability or quality issues, the microgrid could become susceptible to the same problems. The project showed that microgrid operators can disconnect, avoid problems, use the microgrid’s own generation resources to power critical loads, and then reconnect when problems are resolved.

The Chevron Energy Solutions microgrid project is one of nine projects funded through the DOE’s Office of Electricity Delivery and Energy Reliability’s Renewable and Distributed Systems Integration Program. The 5-year project received additional funding from the American Recovery and Reinvestment Act of 2009.

Customer-side microgrids, such as the one at the Santa Rita Jail, are increasingly being installed and operated to reduce costs, improve reliability and security, and reduce emissions.

The unique power needs of the Santa Rita Jail, located in Alameda County, made it an excellent facility for demonstrating the microgrid technology. The 4,000-inmate jail consists of 18 modern housing units. It is considered a "mega-jail," and ranks as the third largest facility of its kind in California. It is recognized as one of the most technologically innovative jails in the world, where robotic systems deliver laundry, supplies, and food to all areas of the 113-acre campus and a modem cook-chill food service operation produces 12,000 economical meals per day. Alameda County occupies most of the East San Francisco Bay Area and includes the cities of Oakland, Berkeley, San Leandro and Alameda.